Epidemiological study designs are often grouped in the general categories of obser- vational studies or experimental studies 250mg flutamide fast delivery. These studies describe the natural course of disease and they do not involve a planned intervention 250 mg flutamide otc. Descriptive studies are essential for estimating the distribution of disease and associated risk factors in populations cheap flutamide 250 mg with mastercard. In general, they are moderately costly but yield important data for public health planning and evaluating disease trends that could help indicate disease etiology. Often they are conducted as cross-sectional studies at one period of time and provide estimates of disease prevalence, defined as the total number of individuals with the disease in a population at a given point of time. A second cross-sectional study conducted on the same population could allow the calculation of disease incidence, defined as the number of newly developing cases of a disease occurring in a defined population over a defined period. Ecological studies, sometimes called correlational studies, use data from groups rather than individuals to identify correlations that could indicate potential risk factors (2). These studies often use available data sources and are therefore very inexpensive to conduct. Although ecological studies are an inexpensive means to identify potential risk factors, caution must be used in interpreting the correlation between aggregate-level data to avoid ecological bias or fallacy (2). This bias occurs when an assumption is made that association observed at the aggregate level holds true at the case or individual level. Case control studies are designed to identify risk factors by comparing exposures or other characteristics of individuals with a disease or condition (cases) to those from a suitable comparison group without the disease or condition (controls). These studies are often called retrospective studies because the exposures or potential risk factors of interests are recalled or measured after the disease has occurred. In general, these studies are less expensive than cohort studies to conduct, but differential recall between cases and controls of past exposures can lead to bias. This kind of recall bias can lead to inaccurate associations of environment exposures with disease. Despite this potential bias, case control studies are extremely helpful in identifying potential risk factors, especially for rare diseases. Cohort studies involve measuring potential risk factors or exposures in disease-free individuals and then following these individuals over a period until some of them develop the disease of interest. These studies can be conducted prospectively in time or, if past exposure data are available, they can be conducted retrospectively. Because the study population is usually followed very closely over a long period, cohort studies can be quite expensive to conduct. However, cohort studies can provide estimates of the true relative risk of a factor with disease. A major advantage of cohort studies is that they can estimate the temporal sequence between exposure and disease. These are experiments where subjects or groups of individuals with equal characteristics are randomly assigned to receive or not receive the therapy or intervention (2). Because the study subjects are randomly assigned to a treatment or a control group and followed over time for health events, these studies are regarded as the most scientifically rigorous methods of hypothesis testing. Epidemiology Subdisciplines The study designs just reviewed form some of the basic tools in a field that is becoming increasingly specialized. Subdisciplines of epidemiology, like those shown in Table 3, each have developed very specific approaches to measuring and modifying disease risk factors, often incorporating newly developed technology and statistical methods. For example, social epidemiology focuses on the complex social distribution and social determinants of health (6). Social epidemiologists take a broad population and life-course perspective, building multilevel models incorporating community measures in addition to risk factors on the individual level. Given the wide pharmacotherapeutic options for treating rheumatic diseases and their variable effects on individuals, pharmacoepidemiology is an extremely important field for rheumatologists. Understanding individual responses to medications is the first step to personalized medicine. Environmental exposures have been implicated in the etiology of some chronic diseases, but quantifying these exposures is often extremely difficult. Environ- mental epidemiologists specialize in measuring the relationships between exogenous Table 3 Examples of Epidemiology Subdisciplines Subdiscipline Social/behavioral epidemiology Pharmacoepidemiology Environmental epidemiology Genetic/molecular epidemiology 44 Part I / Introduction to Rheumatic Diseases and Related Topics environmental agents and health (9). Genetic or molecular epidemiological studies seek to link a particular genotype or biological marker of a specific effect (i. These types of studies combine principles of human and population genetics with classical epidemiological methods. They can be used to help determine disease etiology and also to improve our understanding of disease risk, classification, and progression. Genetic epidemiological studies determine the role of inherited causes of disease in families and in populations. Often, family or twin studies are used to first establish whether there is a genetic component to a disease. Next, segregation analyses are used to estimate the mode of genetic transmission and linkage and association studies are used to estimate the genetic locus and alleles associated with disease. Once the genes and alleles are identified, genetic epidemiologists also evaluate gene gene and gene environment interactions with disease risk. Genetic epidemiology is a particu- larly dynamic field that is being shaped by very rapid improvements in genotyping and bioinformatics technology, falling genotyping costs, and advances in statistical methods. Rheumatic diseases are clinically complex and this presents many methodological challenges in studying these diseases. Some of the major methodological issues in rheumatic disease epidemiology are shown in Table 4. Fortunately, this problem is being addressed by the adoption of very specific criteria to classify cases. The creation and continual refinement of these classification criteria to reflect new disease knowledge greatly improves the ability to conduct epidemiological studies and it allows study results to be more easily compared. The difficulty in identifying individuals with rheumatic disease in populations is another limitation to better understanding the epidemiology of these disorders. The difficulty of diagnosis and variability in disease course and treatments can also affect the ability to identify and track cases for epidemiological investigations over time. For this reason, investigators often use multiple clinic and hospital sources for case ascertainment and employ disease registries to more easily track patients over time. Many of these conditions are thought to be polygenic and involve multiple environmental exposures, and this complicated etiology has resulted in the identification of few potentially modifiable risk factors for rheumatic diseases. The lack of previously identified risk factors can dissuade investigators from carrying out epidemiological studies. However, rheumatic disease classification criteria are by definition restrictive (i. Furthermore, 27% reported pain or stiffness in or around a joint in the past 30 days that began more than 3 months ago. Prevalence was lowest among Asian and Hispanics and highest among Native Americans and Alaska Natives. Arthritis diagnosis and chronic joint symptoms were also more common among individuals with the lowest education and income levels. For a more complete review of the epidemiology of these and other rheumatic diseases, refer to Silman and Hochberg (14). Disease onset can occur at any age, but a majority of cases are diagnosed between ages 40 and 60. Unlike previous diagnostic guidelines, subgroups are not assigned according to severity. Perhaps the broadest range occurs between populations of North American Natives, from 0. Estimates are based on household interviews of a sample of the civilian noninstitutionalized population. Therefore, regardless of gender, higher levels of reproductive hormones may provide an avenue by which primary prevention methods may be established (27). Furthermore, these markers correlate with disease severity (31) and early age of onset (32). It calls into question whether there are common genetic risk factors underlying many autoimmune diseases (30). Additionally, many pharmacogenetic studies are underway to determine the genetic influences on treatment response, partic- ularly toward understanding the pharmacogenetics of methotrexate response (30).
Peracute inammation of the transition cow are very important factors in decid- may cause subtle swelling of the quarter in some peripar- ing the prevalence and severity of new flutamide 250 mg, coliform intra- turient cows that may mask the inammation-related mammary infections in dairy cattle order flutamide 250 mg otc. Regardless of the degree of swelling order 250 mg flutamide with amex, the secre- Chronic cases of coliform mastitis once were thought tion in coliform mastitis (acute) is more watery than that to be rare but now have been routinely conrmed in at in unaffected quarters. Chronically infected as serum-like or watery by most experienced clini- quarters may be nonproductive or may have subclinical cians and is best detected by rst stripping normal mastitis with intermittent areups that mimic other milk from an unaffected quarter onto a black-colored causes of acute mastitis. Unfortunately spontaneous plate, then milking secretions from the affected quarter cure is difcult for the cow that has been chronically onto the normal milk. Rectal temperatures ranging sociated with coliform mastitis predispose affected cows between 104. Patients that tant recumbent periparturient hypocalcemia may be have been treated with high doses of dexamethasone hypothermic rather than febrile. Some affected Rarely cattle with peracute coliform mastitis have cows will shiver and have their hair stand on end as developed lactic acid indigestion following ingestion of early nonspecic signs that are associated with fever and large meals of high-moisture corn. Ophthalmic consequences of the toxemia profound rumen stasis from endotoxemia was thought associated with coliform mastitis may include scleral in- to contribute to malfermentation of the grain. Cows may be- The severity of endotoxic signs varies tremendously in come recumbent from the profound weakness resulting cattle with coliform mastitis. Many cattle affected with acute nosis and may interfere with detection of the mastitis. The coliform mastitis that subsequently was conrmed as udders of all recumbent cattle, especially those in the early resulting from Klebsiella sp. The importance of careful examination of the milk with a black strip plate cannot be overemphasized. Plates should be examined under reected lighting to detect subtle changes that may occur early during coli- form mastitis. Tests based on increased milk pH are used for the detection of coliform mastitis in Europe, but such tests are less available in the United States. Freezing and thawing the samples before inoculation onto media increases the sensitivity of the test but could also kill some sensitive bacteria. Treatment of coliform mastitis has been The individual was recumbent, severely dehydrated, and controversial because of the administration of extra-label acidemic. Many experimental studies acids are better choices for intramammary administration of coliform mastitis emphasize that infection resolves for the treatment of clinical mastitis, whereas the weak spontaneously as a result of the inammatory neutro- bases achieve better tissue levels when given systemically. Penicillin and ampicillin, weak acids, high mortality rate from coliform mastitis. It is impossi- attain limited ratios in the milk of a healthy cow follow- ble, clinically, to distinguish signs that are associated with ing parenteral administration. Systemic ceftiofur and the persistent infection from those of persistent endotoxemia, aminoglycosides have the poorest distribution in mastitis and furthermore continued signs of endotoxemia may patients. Even knowing Results of studies examining experimental and natu- about these studies, the practicing veterinarian may not ral coliform mastitis treatments are highly confusing. In wish to withhold antibiotic therapy when faced with a one eld study, no apparent benet resulted when sys- greatly distressed or litigious owner whose valuable cow temic gentamicin was used in the treatment of coliform becomes gravely ill with coliform mastitis. The reported success in cows treated systemi- majority of experimental studies demonstrate that antibi- cally with gentamicin (to which the organisms were otic therapy confers no benet on induced coliform mas- sensitive) was no better than in cows treated systemi- titis, there are a smaller number of studies that do show cally with erythromycin, even though the causative or- favorable outcomes when severe eld cases are treated ganisms were resistant to erythromycin, or in nontreated with antibiotics such as ceftiofur. All quarters in this study were treated with with the repeated demonstration of true bacteremia in a cephalothin, regardless of the systemic antibiotic cho- proportion of cows with naturally occurring coliform sen. This differs from another study that demonstrated mastitis, are strong arguments in favor of systemic antibi- a benecial effect of ceftiofur treatment in cows with otic administration. It is no wonder that most prac- apy, albeit controversial, should be understood by bovine titioners develop an individual or clinic-based approach practitioners. The pharmacology and likely benets or to the therapy of coliform mastitis in the eld based on risks associated with each antibiotic should be known their own experiences. Currently approved anti- portant that treatment decisions are made within the biotics for use in lactating cattle are listed in Table 8-1. Although the likeli- Studies that report antibiotic susceptibility of gram- hood of sensitivity of the organism to oxytetracycline is negative bacteria causing mastitis have been reported, only moderate, distribution of the drug to the udder and the accumulated data from these studies and re- should be good, and the drug may provide some antiin- views combined with more recent culture and antibiotic ammatory properties within the udder. Nephrotoxic sensitivity results indicate the following: effects may occur in dehydrated cows treated with oxytet- 1. It is impossible to recommend one treatment sporins, and ticarcillin-clavulanic acid work against because of geographic differences in bacterial popula- most coliforms in vitro tions, resistance patterns of coliform organisms present 2. Polymyxin B and cephalothin work against 60% to on each farm, and many other factors. Culture and sensi- 80% in vitro tivity results should be obtained for isolates from each 3. Tetracycline, ampicillin, neomycin, and kanamycin farm to better determine appropriate antibiotic therapy work against 40% to 80% in vitro when faced with an acute coliform mastitis. Inammation and serum leakage into the gland in- New antibiotics such as orfenicol, a derivative of crease the pH of the milk to nearly physiologic levels chloramphenicol that is not associated with aplastic ane- (7. Inammation, cellular debris, and experimental drugs that have been shown to have good decreased ability to diffuse drugs throughout the quarter distribution via systemic and intramammary routes for diminish the effectiveness of antibiotics especially intra- bovine mastitis. Although most farms harbor a multitude of coli- cial effect on the survival rate of endotoxemic cattle. Flor- forms, culture and antibiotic sensitivity results from fenicol is also not approved for lactation-age dairy cows. Historically stripping every 1 or 2 hours has been advocated, but that has now been refuted with respect to outcome, and cur- rent guidelines call for stripping no more than every 4 to 6 hours even in peracute cases. Too frequent stripping may cause the teat sphincter to remain open, allowing other organisms to gain entrance. Alternatively, one or more calves may be placed in a box stall with the affected cow to nurse the quarters frequently. Obviously, individually as to present and future productive and ge- however, in clinical practice, their use is never prophylac- netic value before a decision to treat with antibiotics is tic because clinical signs only appear after endotoxemia made. Abomasal ulceration is the most frequent gastro- live or die on the farm and salvage for meat is not an op- intestinal complication of overdosage, prolonged use, or tion. If the cow s life is in jeopardy and extra-label drugs employment of these drugs (especially unixin meglu- or dosages are deemed necessary to save the cow, the mine) in very dehydrated patients. Renal papillary ne- owner and practitioner are responsible for ensuring ade- crosis and renal infarcts may develop in cattle treated quate withdrawal time. Some clinicians use intramammary cortico- many cases of coliform mastitis are life-threatening, the steroids such as 10 to 20 mg of dexamethasone as a destruction of glandular tissue is generally less than what one-time treatment. Other clinicians administer 10 to occurs with gram-positive infections, and if the cow sur- 40 mg of dexamethasone systemically. Although corti- vives and quickly clears the infection (with or without costeroids may alleviate the inammatory cascade, they antibiotics), return to near maximum production may be present risk of chronic infection and deter defense possible in the next lactation. Corticosteroids should never be used as Supportive measures are extremely important for a maintenance therapy, and shock dosages, such as 100 successful therapeutic outcome in cases of coliform mas- to 200 mg of dexamethasone, have been suggested by titis. Supportive therapy should be administered regard- some clinicians but should be considered as being very less of the decision for or against antibiotic therapy. A low-dose, one-time treatment Frequent milking out of the affected quarter has previ- may be acceptable in nonpregnant dairy cows with coli- ously been considered the most valuable nursing proce- form mastitis, but high-dose or continued treatment is dure. Balanced electrolyte solutions future of the patient, and past experiences of the attend- such as lactated Ringer s solution usually are the best ing veterinarian. Therapeutic guidelines are offered in choice, but severely affected cattle that show signs of Tables 8-1 and 8-2 and Box 8-2. Culture and antibiotic shock coincident with acidemia may require replace- sensitivity testing should be completed in all cases. Other than implementation of good alkalosis is the most common acid-base disturbance in milking management and the provision of a hygienic, off-feed cattle, peracute/acute coliform mastitis is one of clean environment, no reliable specic prevention for the few common illnesses in adults that is often associ- coliform mastitis currently exists. If the patient shows pro- prevention of the disease, or at least, the reduction of found weakness, an acid-base and electrolyte panel severity of the endotoxemia through the use of E. Use of J-5 bacterin has cows that develop coliform mastitis because of the like- also been shown to be of economic benet in well- lihood of clinical or subclinical hypocalcemia. The vaccine is licensed for administra- with coliform mastitis that are able to stand, calcium is tion to dairy cattle at 7 and 8 months of gestation and more safely administered subcutaneously or diluted in then a third time around 2 weeks postpartum. No vaccine can counteract overwhelming envi- authors comment that no true indication exists for the ronmental contamination or poor milking procedures. These studies have been taken to indicate the sionally cause mastitis in dairy cattle. Infections may be potential therapeutic benets of antihistamine therapy epidemic, sporadic, or endemic within a herd. Other nursing procedures include packing the quarter Extra-Label Intramammary Drugs* in ice or snow and application of an udder support.
However flutamide 250 mg overnight delivery, the most recent studies support the idea that oxida tive stress is a significant marker of senescence in different species discount flutamide 250mg with visa. Resistance to oxidative stress is a common trait of long-lived genetic variations in mammals and lower organisms [5 buy cheap flutamide 250mg on-line, 12]. Free radical theory, oxidative stress theory and mitochondrial theory of aging Denham Harman was first to propose the free radical theory of aging in the 1950s, and ex tended the idea to implicate mitochondrial production of reactive oxygen species in 1970s, . According to this theory, enhanced and unopposed metabolism-driven oxidative stress has a major role in diverse chronic age-related diseases [13, 14, 7]. Harman first proposed that normal aging results from random deleterious damage to tissues by free radicals  and subsequently focused on mitochon dria as generators of free radicals . Halliwell and Gutteridge later suggested to rename this free radical theory of aging as the oxidative damage theory of aging , since aging and diseases are caused not only by free radicals, but also by other reactive oxygen and ni trogen species. Increases in mitochondrial energy production at the cellular level might have beneficial and/or deleterious effects . On the other hand, enhanced mitochondrial activity may increase the pro duction of superoxide, thereby aggravating the oxidative stress and further burdening the antioxidant defence system. The mitochondria are the major source of toxic oxidants, which have the potential of reacting with and destroying cell constituents and which accumulate with age. The result of this destructive activity is lowererd energy production and a body that more readily displays signs of age (e. Damaged mitochondria can cause the energy crisis in the cell, leading to senescence and aging of tissue. The gradual loss of energy experienced with age is paralleled by a decrease in a number of mitochondria per cell, as well as energy- producing efficiency of remaining mitochondria. How 334 Oxidative Stress and Chronic Degenerative Diseases - A Role for Antioxidants ever, whether this damage affects mitochondrial function or significantly modulates the physiology of aging has remained controversial [27, 28]. As already mentioned, free radicals can damage the mitochondrial inner membrane, creating a positive feedback-loop for in creased free-radical creation. Oxidative stress from endogenous or exogenous sources can trigger the chain reaction, which leads to accel erated aging process of cells and organisms. But the efficiency of autophagy to consume mal functioning mitochondria also declines with age, resulting in more mitochondria producing higher levels of superoxide . Mitochondria of older organisms are fewer in number, larg er in size and less efficient (produce less energy and more superoxide). Free radicals could also be involved in signalling responses, which subsequently stimu late pathways related to cell senescence and death, and in pro-inflammatory gene expres sion. Other theories of aging Apart from the free radical theory, the aging is explained by many other theories: The Telomere shortening hypothesis (also described as "replicative senescence," the "Hay flick phenomenon" or Hayflick limit) is based on the fact that telomeres shorten with each successive cell division. The telomere shortening hypothesis cannot explain the aging of the non-dividing cells, e. The Reproductive-cell cycle theory states that aging is regulated by reproductive hor mones, which act in an antagonistic pleiotropic manner through cell cycle signaling. This promotes growth and development early in life in order to achieve reproduction, howev er later in life, in a futile attempt to maintain reproduction, become dysregulated and drive senescence . The Wear and tear theory of aging is based on the idea that changes associated with aging result from damage by chance that accumulates over time . The wear-and-tear theories describe aging as an accumulation of damage and garbage that eventually overwhelms our ability to function. Similar are Error accumulation and Accumulative waste theories; Error accumulation theory explains aging as the results from chance events that escape proofread ing mechanisms of genetic code , according to Accumulative waste theory the aging re sults from build-up of cell waste products in time because of defective repair-removal processes. Terman,  believes that the process of aging derives from imperfect clearance of oxidatively damaged, relatively indigestible material, the accumulation of which further hinders cellular catabolic and anabolic functions (e. It describes beneficial ac tions resulting from the response of an organism to a low-intensity stressor. It has been known since the 1930s that restricting calories while maintaining adequate amounts of other nutrients can extend the lifespan in laboratory animals. Additionally, the Disposable soma theory was proposed [36, 37], which postulated a special class of gene mutations with the following antagonistic pleiotropic effects: these hypotheti cal mutations save energy for reproduction (positive effect) by partially disabling molecular proofreading and other accuracy promoting devices in somatic cells (negative effect). The 336 Oxidative Stress and Chronic Degenerative Diseases - A Role for Antioxidants Evolutionary theory of aging is based on life history theory and is constituted of a set of ideas that themselves require further elaboration and validation . Evidence implies that an important theme linking several different kinds of cellular damage is the consequence of exposure to reactive oxygen species [5, 39]. None of the theories explain the ag ing process, as it may be too complex to be covered by only one theory. Perhaps there is no single mechanism responsible for aging in all living organisms . In essence, aging is progressive accumulation through life of many random molecular defects that build up within the cells and tissues. For this reason, only one magic bullet will never be able to prevent or reverse the complex and multicaus al process of aging. The Role of Oxidative Stress on the General Aging Process In order to understand strategies to reduce oxidative stress and aging, it is first important to briefly explain reasons for oxidative stress formation. The most important endogenous sources of oxi dants are mitochondrial electron transport chain and nitric oxide synthase reaction, and the non-mitochondrial soruces: Fenton reaction, reactions involving cytochromes P450 in micro somes, peroxisomal beta - oxidation and respiratory burst of phagocytic cells . Free radi cal reactions have been implicated also as the consequence of exposure to many environmental pollutants, e. Oxidative stress is the direct consequence of an increased generation of free radicals and/or reduced physiological activity of antioxidant defenses against free radi cals. The degree of oxidative stress is proportional to the concentration of free radicals, which depends on their formation and quenching. Causes of increased free-radical production include : Endogenous elevation in O concentration2 increased mitochondrial leakage inflammation increased respiration others Exogenous environment (pollution, pesticides, radiation, etc. There is an oxidative damage po tential, as there is a constant free radical formation in small amounts, which escape the cell defense. Besides the endogenous and exogenous antioxidative protection, the second category of de fence are repair processes, which remove the damaged biomolecules before they accumulate to cause altered cell metabolism or viability . It catalyzes the dismutation of hydrogen peroxide into water and molecular oxygen . Both, glutathione reductase and glucose-6-phosphate de hydrogenase are involved in the glutathione recycling system . Secondary Antioxidant Defenses Although efficient, the antioxidant enzymes and compounds do not prevent the oxidative damage completely. Many of these essential maintenance and repair systems become deficient in senescent cells, thus a high amount of biological garbage is accumulated (e. Age-related oxidative changes are most common in non-prolifer ating cells, like the neurons and cardiac myocites, as there is no dilution effect of damaged structures through cell division . There is an age-related decline in proteasome activity and proteasome content in different tissues (e. On the other hand, proteasome acti vation was shown to enhance the survival during oxidative stress, lifespan extension and maintenance of the juvenile morphology longer in specific cells, e. The total amount of oxidatively modified proteins of an 80-year-old man may be up to 50% . It is likely that changes in proteasome dynamics could generate a prooxidative conditions that could cause tissue injury during aging, in vivo . There appears to be no great reserve of antioxidant de fenses in mammals, but as previously mentioned, some oxygen-derived species perform useful metabolic roles . Exogenous Antioxidant Defenses: Compounds Derived from the Diet The intake of exogenous antioxidants from fruit and vegetables is important in preventing the oxidative stress and cellular damage. Natural antioxidants like vitamin C and E, carote noids and polyphenols are generally considered as beneficial components of fruits and vege tables. Their antioxidative properties are often claimed to be responsible for the protective effects of these food components against cardiovascular diseases, certain forms of cancers, photosensitivity diseases and aging . However, many of the reported health claims are based on epidemiological studies in which specific diets were associated with reduced risks for specific forms of cancer and cardiovascular diseases. The identification of the actual in gredient in a specific diet responsible for the beneficial health effect remains an important bottleneck for translating observational epidemiology to the development of functional food ingredients. When ingesting high amounts of synthetic antoxidants, toxic pro-oxidant ac tions may be important to consider . Adaptive responses and hormesis The adaptive response is a phenomenon in which exposure to minimal stress results in in creased resistance to higher levels of the same stressor or other stressors.
In each study there were more urine predisposes to infection and inuences the cases of lameness in the higher concentrate feeding severity of problems generic flutamide 250mg with visa. The groups fed low to moderate levels of con- terdigital dermatitis is secondary either to skin (and centrate were affected with some lesions of laminitis possibly hoof sole) hypertrophy or to ssures in the despite attempts to minimize the occurrence of ruminal heel horn caused by the bacterial elastases that are acidosis best 250 mg flutamide. The author participated in a trial of rubber ver- capable of cleaving the beta-pleated keratin of the sus concrete ooring in free stall housing purchase 250 mg flutamide otc. The main environmental risk factors seem to ment was awed by the cows available to populate the be manure contact with the skin and anaerobic two barns; the groups were not well matched. Digital dermatitis is an infectious disease of the skin quences of standing on concrete are considered by many affecting cattle older than about 6 months of age to be very important in the development of lesions of anywhere from the vicinity of the dewclaws distally. Pressure exerted on specic portions of the The causal organism(s) have not been conclusively claw may contribute to the observed vascular-derived le- identied, but response to therapy with antibacterial sions of either hemorrhage or necrosis. Cattle claws are drugs and the consistent observation of spirochetes commonly shaped in less than desirable forms. Dry conditions as may occur in and that routine trimming can prevent many of the dry lot or some pasture conditions seem to prevent more severe cases of lameness. It is of interest that the spread of the infection but do not inuence the installation of rubber by feed alleys, in parlor holding severity in already infected cattle. Control is with areas, along alleys connecting pens to the milking parlor, footbathing or spraying with the antibiotics (oxy) and most recently complete alley covering with rubber tetracycline or lincomycin. Thus far there are no data on tic solutions including formalin are used successfully the effects of these changes on lameness, but our un- in footbaths for control. Environmental Risk Factors for Claw Lameness incidence in bullocks housed on slatted oors, 4. Similarly a cross-sectional survey of Dutch focused on the nutritional management of cattle to dairy calves between 2. Ruminal more sole hemorrhages in heifers housed on slatted acidosis is probably a necessary but not independently oors than in straw yards. Subordinate problems and 11 control herds was made during 2 years animals are also more likely to stand in the alley alto- by Dr. There was a correlation between the stall surfaces, either Interpretation of this behavior is that it provides a re- concrete or with a rubber mat, and the occurrence of duction in the danger posed by more dominant cattle. Fewer sole hemorrhages occurred in stalls Housing rst-lactation animals separately from older tted with rubber mats. The cows were in tie stalls, and cows has resulted in a reduction of the negative effects of bedding use was not found to inuence the prevalence these social interactions on the heifers. Great attention has justi- effect of environment on laminitis in free stall housing ably been spent in the past 20 years on improving the compared the problem in two herds with the same design of free stall partitions, beds, and overall dimen- owner and stall design but managed differently because sions. Cow comfort has been a popular theme of the past of the requirements of the manure removal system. Both the proportion of animals standing in the to improve lying time to reduce lameness. The goal of alleys and the proportion of animals standing half in free stall facility design should be to provide a space for the stalls were higher for the herd with more lameness. Cows should enter and exit freely including Increasing the bedding amount for the problem herd lying and rising without interference and ideally spend resulted in amelioration of the lameness. Because Environmental circumstances for dairy cattle thus ap- mechanical loading of the claws contributes very impor- pear to have two possible avenues of inuence on the tantly to the development of the serious lesions of lami- development of laminitis. First are those environmental nitis, evidence of underutilization of stalls is a cause for conditions that inuence feeding behavior. Cows that have had an unpleasant experience in a those conditions that predispose to excessive standing stall are more reluctant to use a stall the next time it is time, and standing on concrete in particular. Those cows that stand half in and half out of ing and lying behavior tend to be synchronized activities stalls are often increasing the load on the rear digits and within a group of cows. Maintenance of the bedding in cattle in an experimental setting have shown that regard- stalls is also critical for use and comfort. Hock lesions are less of feed access, whether 100% can eat at once or 50% a common complaint of many mattress stall designs be- at once, most eating will occur in temporal clusters. Plain concrete or hard rubber mat stalls with bed- have less time available to eat and will slug-feed more ding appear to be the least desirable for overall comfort often. Another notable study stress probably inuences feeding behavior the most made comparison of two free stall designs utilizing adversely with regard to laminitis. These two factors com- Rigg, which prevented side lunging and had no rubber prise the major inuences of environment on feeding mat over the concrete base. Lying time was increased, and behavior with ultimate consequences mediated via ru- standing half in stalls was reduced in the Dutch comfort minal acidosis on the development of laminitis. There were more sole hemorrhages and six cases of Standing time on concrete is heavily inuenced by the acute lameness in the Newton Rigg stalls versus one lame environmental design of dairy facilities and modied by heifer in the Dutch comfort stalls. Synchroniza- For free stall housed herds, the forced standing time tion of behavioral activities again leads a group of cattle imposed by management activities may contribute to to mostly lie down at the same time. The milking parlor should be sized free stall pens prevents some of the subordinate animals to limit holding period time to 3 hours out of every from access to a stall. Other man- may signal the pen is ready to collectively eat or be agement activities such as bedding stalls or veterinary milked, thus preventing that timid animal from lying at work should be organized to minimize the intrusion on all. We believe that there are two primary environmen- group will help minimize slug-feeding. Comfortable stalls stress will redistribute their meals to eat predominately in and heat stress prevention will greatly minimize the de- the morning. This slug-feeding increases the incidence of velopment of lameness resulting from laminitis. Second, and of unknown importance relative to the increase in low rumen pH, is the increase in standing time. Sometimes, apparently when stable ies (Stomoxys calcitrans) are bothersome, they stand in Most upper limb lameness is caused by trauma, although tight groups at one end of a pen. The out- goal of a cow is to be in the center of a group where come of any case will depend on the severity of the injury, the heat stress is likely maximal. Maybe they stand in the what specic structures are damaged, and the enthusiasm stalls because they perceive themselves to be cooler the farm personnel have for nursing disabled or recum- standing than lying down. Most upper limb injuries end in euthanasia or reasons, the slug-feeding and excess standing lead to slaughter. Summer ventilation and prognosis early for those cattle that have no chance of re- strategies to cool cows have the possibility to signicantly covery. Most cattle do not warrant the expense of attempts reduce this seasonal lameness problem. Good hospital pen circumstances with soft bedding Miscellaneous Environmental and no competition for food and water are essential. The softness of moist hooves, as in most free stall housed A second category of upper limb lameness is caused cattle, makes them more susceptible to traumatic lesions by infection either of muscles and tendons or joints. Some oor grooving and some slatted oors Septic arthritis or tendonitis may occur from wounds have such large voids in the surface that the claws of but more commonly occurs in neonates as a result of cows can be injured as they push their claws into the failure of adequate colostrum management and poor grooves or holes. Arthritis and tendonitis caused by from sand bedding that is not screened to exclude parti- M. Many herds have experienced excessive lameness when Stie Injuries cows were placed in facilities with new concrete. For the most part, these problems have been caused by excessive Stie injuries occur most commonly in adult cattle and wear of the soles leading to exposure of the corium. Mounting injuries, falls, slipping on poor footing, vention of this problem of surfaces that are too abrasive and exertional activity in downer cows cause most stie at rst can be done by dragging concrete blocks or scrap- injuries in cattle. Degenerative joint disease also may ing with a steel blade before cattle are introduced to contribute to stie injuries in old cattle or bulls. Conclusions Environmental conditions play a signicant role in the Cranial Cruciate Ligament Injury occurrence of lameness in dairy cattle. Manure and urine Typical signs of acute stie lameness characterized by in constant contact with the hooves and digital skin may exion of the stie and just touching the toe to the predispose to entry of infectious agents that produce le- ground characterize cranial cruciate ligament rupture. Con- Joint distention may be obvious, and the tibial crest may trol is enhanced when hooves and skin are clean and be more apparent than normal. Footbathing with antibacterial solutions in ap- onto the affected limb or the animal is forced to walk, propriately designed and located baths can reduce the palpation of the stie will allow detection of an obvious incidence of lameness resulting from infectious causes. A pull is exerted on the cranial proximal Stie radiograph from cow with a chronic cranial cruci- tibia, which will move into its normal position.
F. Daryl. Maryville University of Saint Louis.
Richmond Rascals. 12 Richmond Hill. Richmond-Upon-Thames. TW10 6QX tel: 020 8948 2250